Oscillating motor driving arrangement



' July 21, 1970 HARMS oscmmme MOTOR muvme ARRANGEMENT Filed July 11,1969 INVENTOR Luhr Harm; BY mam: gm

.. ATTORNEY United States Patent M 3 521 093 OSCILLATING MOTOR DRIVINGARRANGEMENT Liihr Harms, Oberursel, Taunus, Germany, assiguor to BraunAktiengesellschaft, Frankfurt am Main, Germany Filed July 11, 1969, Ser.No. 841,009 Claims priority, application Germany, July 26, 1968,1,763,728 Int. Cl. H02k 7/02 U.S. Cl. 310-49 12 Claims ABSTRACT OF THEDISCLOSURE A driving arrangement for electric hair cutting apparatushaving an armature oscillatable about a predetermined axis and operativeto drive the cutter of the apparatus at a predetermined frequency ofoscillation determined by the mass of the armature. A weight having apredetermined mass is arranged to be selectively coupled to the armatureso that the mass of the resulting oscillating assembly which includesthe armature and the weight changes the frequency of oscillation.

BACKGROUND OF THE INVENTION This invention relates to a drivingarrangement for electric hair cutting apparatus and relates particularlyto such driving arrangement incorporating a frequencyadjustableoscillating system.

Driving arrangements for electric hair cutting apparatus whosecharacteristic frequency can be adjusted and adapted to different powerline frequencies are known and find special application in thosecountries in Which the electric power system consists of a plurality ofdifferent line frequencies.

Such change of the characteristic frequency to a given line frequencymay, on the one hand, be accomplished by adjusting the spring bias onthe oscillating system and, on the other hand, may be effected bychanging the moment of inertia of the system, i.e., by shifting orchanging the predetermined mass of the oscillating system.

For example, in certain conventional oscillating systems for electrichair cutting apparatus, such as electric shavers, the characteristicfrequency of the system may be changed and adapted to a given linefrequency by adjusting the directive or controlling force of a returnspring. In one particular embodiment of such known system, the latterconsists of two movable individual systems including two magnetic arms.In this arrangement, adjustment of the controlling force of the returnspring is effected in such a way that the relative positions of the twomovable systems is not changed and synchronization of their points ofneutral equilibrium, necessary to avoid interfering vibrations, is notdisturbed.

Also known are oscillating systems in which the return springs arehelical or coiled and are disposed at both sides of the swing arm,transversely relative to the armature and positioned intermediatesupports which are axially adjustable and extend perpendicular relativeto the spring axis. These springs are provided with a maximum or almostmaximum number of windings so that their spring constants and,consequently, the characteristic frequency of the system, may beselectively varied by turnably adjusting the springs relative to thesupports.

In a further known oscillating system in which the armature is connectedto a leaf spring, one or more displaceable clamping strips are providedwhich are operative to effect the necessary adjustment of the springconstants and thereby the resonance frequency of the 3,521,093 PatentedJuly 21, 1970 system. The clamps enable adjustment of the span and thefree-swinging length of the spring in such a way that the springconstant corresponds with the magnetic flux of the oscillating system.

However, as a rule, frequency adjustment of the mechanical system bychanging the spring pressure or spring characteristic cannot beaccomplished to such an exact degree as is required for hair cuttingapparatus and this in view of the fact that, in general, the tolerancesinherent with springs, are excessive. To overcome this disadvantage, asystem has been adopted in which frequency adjustment of the oscillatingsystem is effected by reducing the mass of inertia of the system. Tothis end, i.e., to reduce the mass of inertia, a weight in the form of ascrew is added the swing arm. This screen is adjustable in direcv tionof the pivot axis through which the mass of inertia of the system may bevaried and the characteristic frequency of the oscillating system may betuned.

However, this additional mass is permanently connected with theoscillating arm, and is not easily accessible and, during operation ofthe apparatus, is not adjustable with the result that tuning oralignment of the frequency by the operator is practically impossible. Inaddition, with such a system only relatively small frequency adjustmentscan be realized this in view of the fact that the space available in thehousing of the apparatus, and especially in an electric shaver, usuallyis too limited to permit a substantial adjustment of the screw.

SUMMARY OF THE INVENTION Object of the invention is to provide a simpledriving arrangement for electric hair cutting apparatus adapted to beeasily adjusted to a plurality of different line frequencies.

Such a driving arrangement according to the invention comprises anarmature oscillatable about a predetermined axis, motion transmittingmeans operatively connected with the armature, AC current operatedoscillating means adapted to oscillate the armature selectively at aplurality of different predetermined frequencies depending upon thefrequency of the AC current actuating the oscillating means, a Weighthaving a predetermined mass, and adjustable coupling means operative toselectively connect the weight to the armature so that the mass of theresulting oscillating assembly including the armature and the weight isadapted to the selected one of said frequencies.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a partial front sectionalview with cut open portions of a preferred embodiment of the invention,and illustrating the drive arrangement of an electric hair cuttingapparatus;

FIG. 2 is a side view taken on the line 22 of FIG. 1;

FIG. 3 shows the driving arrangement of FIG. 1;

FIG. 4 shows the same view as FIG. 3 but with additional components;

FIG. 5 shows an exploded view of the individual components of theoscillating system incorporated in the arrangement of FIG. 1; and

FIG. 6 schematically shows further particulars incorporated in thearrangement of FIG. 1.

3 PREFERRED EMBODIMENT OF THE INVENTION FIG. 1 shows an electric haircutting apparatus which, for illustration purposes only in this instanceis in the form of an electric shaver the conventional parts of whichhave been omitted or are not described in detail.

The shaver is seen to comprise a housing 1 consisting of two separableshell secions 2 and 3 and a detachable partially open cap section 4 inwhich a gauze-like sheet 5 is arcuately disposed. Cooperating with thesheet 5 is a cutter section 6 which is driven in conventional manner byan AC current oscillating system 7 via a motion transmitting member inthe form of swing arm 8 and is biased against the sheet 5 by a pressurespring 10 disposed around the upper cylindrical section 9 of the arm 8.

The oscillating system 7 is mounted on a plate 11 which, in turn, isconnected to the shell 3 by means of screw members one of which is shownin FIG. 2 and indexed with numeral 12. The system 7 comprises twoelectromagnets which form the oscillating members of the system and ofwhich only the two pole shoes 13 and 14 and the coil members 15 and 16are shown. Mounted on the plate 11 is a fulcrum 17 which pivotablymounts the swing arm 8, the latter being integrally formed at its lowerend with an oscillating armature 18 having a predetermined mass andwhich cooperates with and is oscillated by the pole shoes 13 and 14 witha predetermined frequency during operation of the system. Biasedlaterally against opposite sides of the swing arm 8 are two coil springs19 and 20 which with their outer ends abut against projections 21 and 22mounted on the support plate 11. Provided in projection 21 is a screwmember 23 operative to regulate the neutral or rest position of thearmature relative to the pole shoes 13 and 14. The free end of fulcrum17 is fixedly connected in a recess 24, FIG. 5, of a substantiallyT-shaped bridge member 25 whose yoke 26 is connected to two supports 29and 30 of the plate 11 by means of two screw members 27 and 28. Thisbridge has not been shown in FIGS. 1 and 3 so as to enable a clearerillustration of the more important features, which will hereinafter bedescribed.

Pivotably mounted on fulcrum 17 intermediate the swing arm 8 and thebridge 25 is an additional weight with a predetermined mass and whichconsists of two metal arms .31 and 32 which at their free ends areprovided with substantially cylindrical projections 33 and 34. The metalarms 31 and 32 are biased in the direction of the armature 18 inresponse to presure exerted on the arms by a torsion spring 35. To thisend, the spring member at its two free ends is provided with rightangular sections 36 and 37 which are received in bores 38 and 39 of theprojections 33 and 34, FIG. 4, through which arrangement the arms 31 and32 are pressed against lateral portions of the armature 18, as shown inFIG. 1.

The spring member forms an essential part of an adjustable couplingarrangement operative to selectively connect the additonal weight to thearmature.

This coupling arrangement further comprises a cam member 43 which isturnably mounted in an opening 40 of the bridge 25 via pivot 41. Asshown, the cam member 43 is integrally formed with a disc-shaped member42 and has a substantially part circular cross section. The cam member43 is turnable by means of an adjusting member in the form of knob whichis connectably received in an opening 44 in the pivot axis, FIGS. 1 and2. The cam member 43 is disposed intermediate the arms 31 and 32, FIG.2, and is turnable between a first lower and a second upper position inorder to connect and disconnect the weight relative to the armature. Inthe first position, as shown in" FIG. 1, the cam member is out ofengagementwith' the arms 31 and 32 and, under pressure of the springmember 35, the arms operatively engage lateral adjacent portions of thearmature 18. In changing the angular position of the cam member, i.e.,turning it from its first lower position to its second upper position,FIG. 3, the cam member, against the bias of spring 35, moves therespective arms away from the armature and out of engagement therewith.With cam member 43 in its upper position the arms 31 and 32 are engagedby lateral portions of the cam member in which condition the arms areidle while with the cam member in its lower position the arms are out ofengagement with the cam member in which condition the projections 33 and34 are bi-assed against the armature whereby the additionalpredetermined mass of the respective weight sections is added to thepredetermined mass of the armature, as a result of which upon actuationof the armature by the electromagnets, the resulting oscillatingassembly including the armature and the respective weight sections,causes a reduction in the characteristic frequency of oscillation of theapparatus.

Further provided are recesses 46 and 47 which are formed in the arms 31and 32 to insure that when the cam member is in its lower or weightconnecting position, the arms during oscillation do not engage the cammember. However, these recesses are also dimensioned so that duringoscillation of the arms with the armature, they are operative to limitthe extent of oscillating movement of the assembly in case offluctuations in the line frequency.

As shown, the knob 45 extends outwardly through an opening 48, FIG. 2,of the respective shell 2 and, as such, is easily accessible. The knob,as will be appreciated, may have any suitable form or configuration.

Operation of the drive arrangement as hereinbefore described will now bediscussed in more detail.

The driving arrangement 7 of the electric shaver which comprises theswing arm 8 with the spring member 10, the cutter block 6 andoscillating armature 18 and the spring members 19 and 20, has acharacteristic frequency which is determined by the mass of theoscillating components and the spring members and is synchronized with aline frequency of, for example, 60 c.p.s.

The additional mass constituted by the spring member 35 and the two arms31 and 32 with their respective projections 33 and 34, is dimensioned sothat the characteristic frequency of the oscillating system is reducedfrom 60 c.p.s. to 50 c.p.s. when the additional mass is coupled to themass of the oscillating system. This condition is illustrated in FIG. 1,and the electric shaver is now ready to be connected to a line frequencyof 50 c.p.s.

If, on the contrary, it is required that the arrangement 7 should beoperated at a frequency of 60 c.p.s. then all that is necessary is toturn the adjusting knob 45 from the position shown in FIG. 1 to theposition of FIG. 3. in which condition the two arms 31 and 32 and theirrespective projection are expanded and disengaged from the armature 18by cam member 43. At this point the arms and projections do no longeroscillate and are idle as a result of which the frequency of theoscillating system is returned to 60 c.p.s.

The electric shaver further comprises conventional current selectorswitch arrangement operative to adapt the apparatus to the respectiveline voltage, for example v. or 220 v.

To this end, and as shown in FIG. 6, a selector knob 45 is provided witha first gear wheel 49 operative to interlock with a second gear wheel50, which in turn is rigidly connected with a contact finger 51 of theswitch arrangement 52. The gear wheels are dimensioned so that rotationof the knob 45 through corresponds to rotation of the contact finger 51through 90. The contact finger 51 sweeps over four contacts 54, 55, 56and 57 which are disposed at 90 angles relative to one another on aninsulating plate 53 of the switch arrangement 52 and are interconnectedwith corresponding windings in the coil members 15 and 16. The contactfinger 51 is in terconnected with one pole of a power supply plug, notshow, via a wire 58. The knob 43 is interconnected with the contacts ofthe power supply selector in such a way that the following combinationsof line currents and fre quencies are available:

Contact 54110 v., 60 c.p.s. Contact 551 10 v., 50 c.p.s. Contact 56-220v., 60 c.p.s. Contact 57220 v., 50 c.p.s.

Indicating means may be coupled to the gear wheels 49 or 50 so as toreadily indicate the respective current setting of the shaver.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting features,that, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent is:

1. A driving arrangement for movable cutters of shaving apparatus or thelike, comprising, an armature oscillatable about a predetermined axis;motion transmitting means operatively connected with said armature; ACcurrent operated oscillating means adapted to oscillate said armatureselectively at a plurality of dilferent predetermined frequenciesdepending upon the frequency of the AC current actuating saidoscillating means; a weight having a predetermined mass; and adjustablecoupling means operative to selectively connect said weight to saidarmature so that the mass of the resulting oscillating assemblyincluding said armature and said weight is adapted to the selected oneof said frequencies.

2. An arrangement as defined in claim 1, wherein said weight comprises aplurality of sections.

3. An arrangement as defined in claim 1, wherein said coupling meanscomprises resilient means arranged to bias said weight in one directionrelative to said armature.

4. An arrangement as defined in claim 1, wherein said weight comprises aplurality of sections and said coupling means comprises resilient meansoperative to bias said sections in a direction toward engagement withsaid armature.

5. An arrangement as defined in claim 1, wherein said weight comprises aplurality of sections and said coupling means comprises a resilientmember having portions connected only with said sections and engaged tobias said sections in one direction relative to said armature.

6. An arrangement as defined in claim 5, wherein said sections arepivotable about said predetermined axis and flank said armature, saidresilient member being a torsion spring arranged to bias said sectionsagainst the adjacent portions of said armature.

7. An arrangement as defined in claim 1, wherein said weight comprises aplurality of sections including a pair of sections flanking saidarmature, and wherein said coupling means includes a first portionoperative to move said sections toward and into engagement with saidarmature and a second portion operative to move said sections away fromengagement with said armature, one of said portions comprising resilientmeans and the other of said portions comprising cam means.

8. An arrangement as defined in claim 7, wherein said sections arepivotable about said predetermined axis and have followers flanking saidcam means said cam means being movable between a plurality of positionsto thereby move said respective sections away from said armature inresponse to movement from a first to a second position thereof.

9. An arrangement as defined in claim 1, wherein said coupling meanscomprises a rotary cam, and further comprising adjusting means forchanging the angular position of said cam.

10. An arrangement as defined in claim 1, wherein said weight comprisesa plurality of sections and wherein said coupling means comprises aportion which is stationary relative to said sections when the weight iscoupled to said armature, said position including means for limiting theextent of oscillating movement of said assembly.

11. An arrangement as defined in claim 10, wherein said stationaryportion is a rotary cam and said sections have recesses flanking saidcam, said cam having a projection which extends into one of saidrecesses in each end position of said assembly.

12. An arrangement as defined in claim 1, wherein said oscillating meanscomprises electromagnet means having a plurality of windings and furthercomprising selector means operative to connect a selected winding to anenergy source in response to actuation of said coupling means by anadjusting member.

References Cited UNITED STATES PATENTS 1,891,486 12/1932 Wahl 310292,259,131 10/1941 Fleischer et al. 31029 3,086,133 4/1963 Tolmie 31038 X3,343,011 9/1967 Daniels et al 3l029 X DONOVAN F. DUGGAN, PrimaryExaminer US. Cl. X.R.

